In this Monday, May 7, 2018 photo, hundreds gathered for a candlelight vigil for missing 16-year-old Jake Wilson at Wolf Creek Landing in La Porte City, Iowa. The vigil was to show support for Jake's family and friends and a reminder that he is in everyone's thoughts as the search and investigation continues.(Photo: Matthew Putney/The Courier via AP)

Authorities looking for an autistic Iowa teenager who vanished more than a month ago asked the public Wednesday to help raise money for an excavator who has volunteered his time and machinery in the search.

Jason Even, owner of Veracity Excavating LLC, was expected to spend at least 10 hours each day for four to five days next week using his excavator in water searches for Jake Wilson, a 16-year-old who disappeared when he went for a walk to Wolf Creek on the night of April 7 in La Porte City. Even's efforts will help officials clear their search from the creek to the Cedar River, authorities said.

The city's police chief, Chris Brecher, said it would have cost the city a couple hundred dollars each hour to pay someone to provide and use the machinery Even has volunteered to operate. Because Even has taken time out of his workday, officials hope to reimburse him by raising about $10,000, Brecher said.

In an earlier excavation, Even spent a day preparing and another on the creek with his machinery, grabbing logs out of the water and setting them aside as searchers in dry suits looked for any sign of Jake upstream and downstream.

Six members of theJohnson County Metro Dive Team walk in Wolf Creek in La Porte City during a search for Jake Wilson, an autistic teenager who has been missing since Saturday night. Luke Nozicka / The Register

Six members of the Johnson County Metro Dive Team walk in Wolf Creek in La Porte City during a search for Jake Wilson, an autistic teenager who has been missing since Saturday night. Luke Nozicka / The Register

Six members of theJohnson County Metro Dive Team walk in Wolf Creek in La Porte City during a search for Jake Wilson, an autistic teenager who has been missing since Saturday night. Luke Nozicka / The Register

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Authorities have asked people who want to donate to send cash or checks made out to the La Porte City Fire Association to City Hall at 202 Main St. The memo should be about the excavation project and the search for Jake, the chief said.

Even, a La Porte City resident, could not be reached to comment Wednesday morning.

Brecher described Even as a determined and motivated volunteer. He once told the searchers if it were his child missing, he would hope someone like him would come out to help, the chief said. Even and his wife and son also assisted in previous land searches, when hundreds turned out to look for the missing teenager on foot.

Searchers have combed through about 90 percent of the creek, which the chief described as his team's "main culprit" and "wild card." Because of recent flooding, crews will have to wait until the beginning of next week to continue their searches in the water, Brecher said.

"The last thing we have to cross off our list is the creek," he said.

The La Porte City Fire Department posted on its Facebook page Wednesday, asking for donations. The post said that by the end of the search, they will leave "no log or log jam untouched."

Using sonar, authorities flagged the area of the creek that had pockets as deep as 15 feet, but they found no sign of Jake. Authorities have set up fences in the creek, so they know what comes downstream, the chief said.

His mother, Megan Neiswonger, has said Jake has autism with a mild intellectual disorder and functions at the level of a 9-year-old.

Dogs trained to sniff for decomposing human flesh indicated Jake may be in the creek, though Brecher said authorities do not take the suggestion as definitive. Authorities have found no information to suggest a crime was committed in Jake's disappearance, though police are not ruling out the possibility of an abduction.

In the coming weeks, officials may again call on volunteers to search on land once the flooded waters recede.

Jake, who stands about 5 feet, 6 inches tall and weighs 135 pounds, was last seen at 9 p.m. April 7 going for a walk to Wolf Creek in town. He was wearing a brown zip-up hooded sweatshirt, dark pants and cowboy boots.

Temperatures were unusually cold for April that night, with nearby Waterloo setting a record low of 12 degrees the morning after Jake disappeared.

"The outpouring of help and support from the community has been amazing, but we cannot perform this operation without the community’s support," the fire department wrote on Facebook. "We have received support and sponsorship to get started, but we'll need help funding this operation."